Investment Securities - Reconciliation of Available-for-Sale Securities (Detail) $ in Thousands	Mar. 31, 2024 USD ($) security	Dec. 31, 2023 USD ($) security	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 1,004,333	$ 1,035,238
Gross Unrealized Gains	113	115
Gross Unrealized Losses	(90,417)	(89,071)
Allowance for Credit Losses	0	0	$ (160)	$ (310)
Total	914,029	946,282
Less Than 12 Months	9,401	3,976
Less Than 12 Months	24	4
12 Months or Longer	658,251	679,756
12 Months or Longer	$ 145,262	$ 133,942
Number of Securities | security	538	542
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value	$ 667,652	$ 683,732
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Accumulated Loss	145,286	133,946
U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	324,367	339,364
Gross Unrealized Gains	92	99
Gross Unrealized Losses	(19,570)	(19,694)
Allowance for Credit Losses	0	0
Total	304,889	319,769
Less Than 12 Months	0	0
Less Than 12 Months	0	0
12 Months or Longer	8,913	8,956
12 Months or Longer	$ 499	$ 499
Number of Securities | security	3	3
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value	$ 8,913	$ 8,956
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Accumulated Loss	499	499
Mortgage-backed securities, residential
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	314,413	320,947
Gross Unrealized Gains	12	16
Gross Unrealized Losses	(36,346)	(34,546)
Allowance for Credit Losses	0	0
Total	278,079	286,417
Less Than 12 Months	5,208	285
Less Than 12 Months	8	2
12 Months or Longer	263,239	274,528
12 Months or Longer	$ 57,881	$ 52,163
Number of Securities | security	184	183
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value	$ 268,447	$ 274,813
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Accumulated Loss	57,889	52,165
Collateralized mortgage obligations, residential
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	146,080	150,726
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(13,874)	(13,656)
Allowance for Credit Losses	0	0
Total	132,206	137,070
Less Than 12 Months	0	0
Less Than 12 Months	0	0
12 Months or Longer	9,201	9,447
12 Months or Longer	$ 2,878	$ 2,796
Number of Securities | security	10	11
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value	$ 9,201	$ 9,447
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Accumulated Loss	2,878	2,796
Mortgage-backed securities, multifamily
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	851	856
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(184)	(180)
Allowance for Credit Losses	0	0
Total	667	676
Less Than 12 Months	0	0
Less Than 12 Months	0	0
12 Months or Longer	3,449	3,494
12 Months or Longer	$ 677	$ 651
Number of Securities | security	3	3
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value	$ 3,449	$ 3,494
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Accumulated Loss	677	651
Collateralized mortgage obligations, multifamily
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	45,806	46,541
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4,033)	(4,045)
Allowance for Credit Losses	0	0
Total	41,773	42,496
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	41,313	44,561
Gross Unrealized Gains	8	0
Gross Unrealized Losses	(412)	(868)
Allowance for Credit Losses	0	0
Total	40,909	43,693
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	19,013	19,699
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(605)	(571)
Allowance for Credit Losses	0	0
Total	18,408	19,128
Less Than 12 Months	4,193	3,691
Less Than 12 Months	16	2
12 Months or Longer	371,272	380,787
12 Months or Longer	$ 82,504	$ 77,377
Number of Securities | security	337	341
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value	$ 375,465	$ 384,478
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Accumulated Loss	82,520	77,379
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	112,490	112,544
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(15,393)	(15,511)
Allowance for Credit Losses	0	0
Total	97,098	97,033
Less Than 12 Months	0	0
Less Than 12 Months	0	0
12 Months or Longer	2,177	2,544
12 Months or Longer	$ 823	$ 456
Number of Securities | security	1	1
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value	$ 2,177	$ 2,544
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Accumulated Loss	$ 823	$ 456